'Impurity' in the Bible

"A man who is clean shall gather up the ashes of the heifer, and lay them up outside of the camp in a clean place; and it shall be kept for the congregation of the children of Israel for a water for impurity: it is a sin offering.

Whoever touches a dead person, the body of a man who has died, and doesn't purify himself, defiles the tabernacle of Yahweh; and that soul shall be cut off from Israel: because the water for impurity was not sprinkled on him, he shall be unclean; his uncleanness is yet on him.

But the man who shall be unclean, and shall not purify himself, that soul shall be cut off from the midst of the assembly, because he has defiled the sanctuary of Yahweh: the water for impurity has not been sprinkled on him; he is unclean.

It shall be a perpetual statute to them: and he who sprinkles the water for impurity shall wash his clothes, and he who touches the water for impurity shall be unclean until evening.

everything that may withstand the fire, you shall make to go through the fire, and it shall be clean; nevertheless it shall be purified with the water for impurity: and all that doesn't withstand the fire you shall make to go through the water.